a Bone-Deep Risk for Heart Disease

Gina Kolata in The New York Times:

It’s been one of the vexing questions in medicine: Why is it that most people who have heart attacks or strokes have few or no conventional risk factors? These are patients with normal levels of cholesterol and blood pressure, no history of smoking or diabetes, and no family history of cardiovascular disease. Why aren’t they spared? To some researchers, this hidden risk is the dark matter of cardiology: an invisible but omnipresent force that lands tens of thousands of patients in the hospital each year. But now scientists may have gotten a glimpse of part of it. They have learned that a bizarre accumulation of mutated stem cells in bone marrow increases a person’s risk of dying within a decade, usually from a heart attack or stroke, by 40 or 50 percent. They named the condition with medical jargon: clonal hematopoiesis of indeterminate potential.

CHIP has emerged as a risk for heart attack and stroke that is as powerful as high LDL or high blood pressure but it acts independently of them. And CHIP is not uncommon. The condition becomes more likely with age. Up to 20 percent of people in their 60s have it, and perhaps 50 percent of those in their 80s. “It is beginning to appear that there are only two types of people in the world: those that exhibit clonal hematopoiesis and those that are going to develop clonal hematopoiesis,” said Kenneth Walsh, who directs the hematovascular biology center at the University of Virginia School of Medicine.

…“Some mutations are just markers of past events without any lasting consequence,” said Dr. David Steensma, a blood cancer specialist at Harvard Medical School and Dana-Farber Cancer Institute. But others, especially those linked to leukemia, seem to give stem cells a new ability to accumulate in the marrow. The result is a sort of survival of the fittest, or fastest growing, stem cells in the marrow. “Some mutations may alter the growth properties of the stem cell,” said Dr. Steensma. “Some may just make the stem cell better at surviving in certain less hospitable parts of the bone marrow where other stem cells can’t thrive.”

More here.